Abstract

X-Ray studies of the structure of the high-temperature phase and the orientational phase transition of carbon tetrafluoride have been performed. It has been found that possesses a monoclinic cell with the parameters , , , and , which is similar to the unit cell of the high-temperature phase of silane . In both substances, the high-temperature phase contains molecules which are oriented in 32 different ways in the monoclinic lattice. It is pointed out that the structures determined for and are related to the structures of the low-temperature phases of heavy methane tetrahalides and . It is suggested that the orientational structures of and the low-temperature phases of heavy methane tetrahalides are very similar to one another. It is determined that the phase transition in is first-order phase transition, just as in silane, and is accompanied by a large volume jump reaching .